This invention relates generally to pitot type centrifugal pumps. More particularly, this invention relates to an improved pitot tube having a rib or guide vane therein extending from the inlet to the outlet of the pitot tube.
Centrifugal pumps of the pitot type are well known and are illustrated by U.S. Pat. No. 3,776,658 issued Dec. 4, 1973, to John W. Erickson and by U.S. Pat. No. 3,999,881 issued Dec. 28, 1976, to Walter W. Crichlow.
Particular reference is made to the Erickson patent which, in FIG. 2, illustrates a rib or flow vane that is located in the pitot tube. However, it will be noted that the rib illustrated therein extends from a radial portion of the pitot tube into the outlet thereof.
In such pumps, problems have been encountered with the loss in pump efficiency caused by the external drag due to fluid passing over the exterior of the pitot tube and due to pressure loss as a result of internal drag as fluid flows through the interior of the pitot tube. In attemping to alleviate the external drag loss, which is maximum at the inlet portion of the pitot tube, the exterior configuration of the pitot tube has been designed as an airfoil with the tube being reduced to its minimum width or chord as compared to its thickness. In an effort to alleviate the internal drag loss, flow directing ribs or vanes illustrated in the Erickson patent have been utilized.
An object of the invention is to provide an improved pitot tube that reduces both external and internal drag and thereby improves the efficiency of a pitot type centrifugal pump in which the improved pitot tube is used.